1. Field of the Invention
This invention relates to a television receiver, and more particularly to PIP (Picture In Picture) type and POP (Picture Out of Picture) type television receivers in which a plurality of images are displayed in one screen.
2. Description of Related Art
In general, it is well. known in the art to provide a television receiver having a so-called PIP or POP function in which a plurality of screens are overlapped on a single screen and displayed there. In these television receivers, it is possible to see various kinds of different images in a simultaneous manner. For example, it becomes possible to see a news program while enjoying a movie program.
Such a television receiver as described above having a PIP or POP function is provided with a memory in it, wherein writing-in and reading-out operations for the image signal are alternatively repeated in respect to the memory to produce a reduced image.
In the television receiver having the PIP function, displaying is carried out by overlapping a produced reduced image onto a part of not-reduced image. In addition, normally, sound corresponding to this non-reduced image is outputted through a speaker. In turn, in the television receiver having a POP function, a plurality of image signals are processed to be reduced in size and displayed in matrix on the screen. Additionally, sound corresponding to the image selected from a plurality of reduced images is outputted through the speaker (in the following description, the image from which sound is outputted is called a main screen, and an image through which no sound is outputted is called as a sub-screen.)
However, in the television receiver having PIP function or POP function, there is a problem that a viewer can acknowledge the content of program as regards the main screen where sound is outputted, although the content of program as regards the sub-screen having no sound outputted is hardly understood.
In turn, it is well known in the art to provide a television receiver having a closed caption function for displaying a character caption to assist a physically handicapped viewer.